M. Heydari-Malayeri - Paris Observatory

The closest star to the Sun, lying 4.24 → light-years away.
Other designations: α Centauri C, GL 551, HIP 70890, or simply Proxima.
It is the faintest of the three stars that make up the
→ Alpha Centauri system.
Proxima Centauri is a → red dwarf of
→ spectral type M6 Ve. It has a magnitude of +11.0, but undergoes
sudden brightness increases of up to 1 mag lasting several minutes.
Proxima is a late-type → flare star
with a rotation period of ~ 84 days.
Its mass is about 0.123 → solar masses
or 129 → Jupiter masses.
Proxima orbits the binary system AB at a distance of about 15,000
→ astronomical unit (AU)s,
with a period
of approximately 550,000 years (Kervella et al., 2016, arXiv:1611.0349).
In about 200,000 years it will be
at the same distance as AB and in 240,000 years it will be farther to Sun than
AB. It has an → effective temperature
of only around 3,050 K, a luminosity of
0.15 per cent of that of the Sun, a measured radius of 14 per cent of
the radius of the Sun and a mass of about 12 per cent of the mass of
the Sun. An → exoplanet, named
→ Proxima b, has been discovered orbiting our
nearest neighbor star.
Proxima experiences a seven-year activity cycle, similar to the Sun's 11-year
cycle (B. J. Wargelin, B. J. et al., 2016, arXiv:1610.03447).
But unlike the Sun's relatively moderate flares, Proxima's
outbursts of X-ray and ultraviolet radiation could prove deadly for
any hypothetical life on its planet, Proxima b.